Second is the fact that the player accused exploited what he knew was a loophole to flip his duchy. His earlier post gives me the feeling he knew he shouldn't have been able to flip the last duchy in the realm, when he said he felt the capital flip was a bug. Surely then he would have known you cannot change allegiance with the only duchy remaining.
Except that he was told that the first one
wasn't a bug. If you thought the first one was a bug, were told it wasn't, I think it's highly understandable to go "hm, well this wouldn't be a bug then either".
And for the first point, yes, not friendly. Very Lurian. Backstabbing and infighting galore.